Posted
by
Soulskill
on Friday March 28, 2014 @08:30AM
from the not-recommended-for-hurricane-areas dept.

Daniel_Stuckey writes: "In far-flung rural Alaska, where electricity can cost as much as $1 per kilowatt hour — more than 10 times the national average, according to the New York Times — a wind turbine encased in a giant helium balloon is about to break a world record. The Bouyant Air Turbine (BAT) is about to be floated 1,000 feet into the air in the name of cleaner, cheaper, and mobile energy. That single airborne grouper—it's sort of a hybrid of a blimp, a kite, and a turbine—will power over a dozen homes. The BAT is the brainchild of Altaeros, a company founded by MIT alumni, and, if everything goes according to plan, it's going to be the highest-flying power generator in history. Since winds blow stronger and more consistently the higher above the ground you go, and the hovering BAT harnesses that gale and sends electricity down to earth through the high-strength tethers that also hold the machine steady. "

This can never scale due to helium scarcity. While even low-quality helium would undoubtedly work for this application, the quantities required to build these at scale would drive the price through the roof.

These are unmanned. So even if a tiny fraction burn up (due to lightning or whatever), I don't see how that would be much of a problem. Hydrogen burns very quickly, so would be consumed before it hit the ground. Just make sure they are tethered so they don't fall on a populated area.

These are unmanned. So even if a tiny fraction burn up (due to lightning or whatever), I don't see how that would be much of a problem. Hydrogen burns very quickly, so would be consumed before it hit the ground. Just make sure they are tethered so they don't fall on a populated area.

Just add a parachute pack lashed to the bottom. The balloon burns, the weight causes the parachute to rotate to above the falling structure and an altimeter deploys the parachute before it hits the ground.

You could make this pretty reliable if you separate the hydrogen lifting cells from the turbine/parachute system so an incineration would just involve attaching new balloons and sending the whole thing back up.

Well that's the idea of working around the hydrogen. You offset the hydrogen cells so they're expendable and under heat release the gas quickly, away from the turbine. The parachute gets enough aerodynamics so when it falls it acts like a drogue and pulls itself above the turbine before deploying.

Hydrogen leaks easily and every electrical contact in the generation systems is a potential ignition point. Plus others. While they might not be prohibitive risks, it might still be better to avoid them.

Use part of the electricity generated to maintain hot air? Air gap insulation and other reduced weight methods?

But less easily than helium through non-metallic materials. Even a party balloon will hold hydrogen for days. This thing will have less permeable material, and a much higher volume/surface ratio, so it should be able to stay up for weeks before needing a hydrogen top up. It might even be able to make its own H2 by collecting condensation and doing electrolysis.

every electrical contact in the generation systems is a potential ignition point.

It is suspended in a gale force wind. It is extremely unlikely that the hydrogen slowly diffusing through the covering will build up enough to ig

Interesting. Is that because hydrogen is diatomic, and thus always bigger than monoatomic helium even though the atoms themselves are smaller?

Basically, yes. H2 has a bigger radius than monoatomic helium. But H2 can be absorbed into metal, embrittling the metal in the process. The electrons will disassociate, and the protons can then drift through the metal and diffuse out the other side. So if the container is metal, the H2 will leak out faster, otherwise the helium will.

Disclaimer: I am a programmer, not a chemist. So if you are building a blimp or hydrogen storage facility, you might want to double check all of this.

This discussion prompted me to finally investigate what is involved to accomplish the logical conclusion to lighter-than-air flight: vacuum airships [wikipedia.org] (spoiler alert: materials science state of the art means it's currently science fiction).

However, this made me wonder about the possibility of using a reduced pressure airship filled with helium or hydrogen. Not a vacuum, but with the lift gas pressure such that the propensity to leak was in equilibrium with the atmosphere. This would require material support s

Vacuum, of course, has less mass than either H2 or He. But mass is the wrong way to look at it. You should be looking at "bouyancy". H2 is half the weight of helium, so twice as good, right? Wrong. H2 is 7% the mass of air, so it gives a buoyancy of 93%. Helium gives a buoyancy of 86%. So that is only a 7% difference in lifting capacity. Vacuum gives a buoyancy of 100%, but that is only 7% better than H2. All the problems that come with maintaining the vacuum, and dealing with the pressure differen

Just make sure they are tethered so they don't fall on a populated area.

The only reason these are necessary is that the residents live in sparsly populated areas. If more people lived there the infrastructure cost of traditional electric delivery would be justifiable. From TFA, a turbine could power "dozens" of homes. In the biggest state in the US, a dozen homes is a rounding error in population density.

The only reason these are necessary is that the residents live in sparsly populated areas.

They are deployed first where electricity is $1/kwh, but if they can be scaled up and mass produced, we could use them everywhere. If you go up high enough, you can almost always find strong winds. Unlike many other renewables, these could be used for steady baseload power. There is a lot of potential for this technology.

Well as its doesn't carry any passengers there should not be a huge problem - though NIBYS can be strange. People complained about fuel cell powered buses in London and quoted the Hindenburg as an example of why the buses where not safe.

You're correct about the helium scarcity, but a wind sail generator such as this could probably be modified to produce it's own heated air to stay aloft, a technology already in widespread use in ballooning.

If you check out one article this week, make it this one... these things are crafty cool.

This system isn't designed for general or widespread use. The article specifically mentions industrial and construction use, and the artist's rendition shows them in use at a bridge construction site. So it would be in place of diesel generators and the like, and launched only when needed daily as weather permits to save money over using expensive diesel.

Helium is not scarce at all. It is the second most abundant element there is. Currently (on Earth) there is 3000 metric tons produced annually, with 78% of the global supply existing within the United States.

Helium mixes with any bladder material out there today. Sure low quality helium will work, but it needs to be 100% helium on the inside--that will be a nightmare to manage.

Also the carbon footprint to mine all that helium and make all that high tech cable more or less than the power it puts out over a year? My guess it it's actually inefficient. Mind that the weather issues this thing screams out (i.e. can be used in 1% of the world's normal conditions).

No, only the people investing in this are idiots, the ones collecting the money are quite clever.

Its really difficult to imagine that this is cheaper per power output than a conventional generator. the balloon is big, fragile and probably limited lifetime. Subject to weather, ice, lightning, etc. The supports are not at all trivial - picture holding a balloon on a windy day - the wind X tether will tend to push the balloon downwards - this will significantly limit the max wind speed where this ca

probably limited lifetime - so don't diesel generators, especially if you're using them for prime power.Big - not a problem in remote areasFragile - Remember Bigalow? The guy designing/building Inflatable space stations? A ballon doesn't have to be fragile if you build it out of the right materials.

Expense - part of the reason for the $1/kwh electricity is the cost of moving diesel into the area. Often it has to be flown in! If the turbine system can avoid fuel having to be brought in that way, it's a m

This electrical cable can function as a tether. Maybe a steel cored, twisted aluminium strands cable (as used in medium and voltage transmission) would offer both low electric resistance, high strength, high reliability,...(P.S. I have small lengths of that kind of cable at home. It's probably overkill for a 10-houses sized balloon, but it can be built in smaller gauges)

Fine, you found them out. This is actually just a stalking horse for materials testing for MIT's secret space elemavator protect. All the nerds are going to rapture to outer space to get away from the rest of us dangerously crazy motherfuckers.

I won't comment on whether or not this will work, but in bush Alaska that $1 per Kilowatt Hour is during the prosperous warm times when the fuel to run the diesel generators doesn't have be flow in because of pack ice or a fuel barge delayed because the Coast Guard is holding it for repairs. Now imagine sitting way out on the Aleutian chain where it blows like hell for long periods of time and barges ice over. I once had to wait, through a fuel rationing for a month, for fuel in the middle of winter. One ye

Depends on how you count "solar wind" vs power generation. If you include photo-electric potential, the solar wind is very strong, power generation wise, and because of the low gravity and turbulence environment, you can make huge structures to capture it very efficiently.

You can even get higher if you use staged balloons. At some point, the cable gets too heavy to support its own weight. If you use multiple stages in the cable, you can make it much longer and therefore catch more wind. I don't know what the optimum altitude for such a balloon is (at some point the reduced air density would make the efficiency decrease with altitude). This principle was already demonstrated with staged sailplanes.

If you want it to go higher, you're going to need to make the cable longer. If the cable gets longer, the conductors are going to have to get thicker. Barring room-temperature superconductors, making it go higher is probably not practical.

The technology of blimps is fraught with challenges not least of which are helium's availability, ground interaction (including launch, landing, and tethering/shelter on ground) and a sensitivity to weather. I've worked with a stream-lined tethered blimp 20' long with a camera and radar payload. In 20 knots of wind, the bugger had to be brought down... not trivial. The whole operation worked best, and safest, in NO WIND. So, the idea of using a tetheredhigh air resistance blimp to supply very little

And, as Tigger told Piglet, you just can't argue with a word like "fraught."

Alaska has different efficiencies than the continental US. Getting a construction crew up there to make a ground based windmill is expensive. Basing anything large in the Alaska soil is expensive, if not impossible in the Permafrost. Fuel costs (away from the pipeline) are high due to transport costs.

Oh and any enemy wanting to take out your power or know where you are would just find and shoot down the flippin' blimp and then you...

... fire up your diesel generator?

The military is already flying blimps in combat zones, typically sensor platforms to give good 'eye in the sky' intel for a base and it's surrounding area. Also, it's more difficult than you think to target something that's pretty far up in the sky, and if insurgents/terrorists have that capability I'm more worried about them targetting manned aircraft with that capability than trying to take out a floating generator.

Google bought Makani, which endeavors to produce a kite generator which provides a far larger 'effective' surface to capture wind energy. It is also entirely safe (glider), and doesn't use our precious helium up.
Google will get it done...
http://www.google.com/makani/ [google.com]

If you're going to stick these in the air, why not join them with something like solar energy as well? I believe there are some decently efficient lightweight modern solar panels, so you could have a combined fan/solar source. Since it's floating, it should be above most sources of shadow etc.

Aerostats are a real thing. They have the normal aircraft warning lights.
This one time, an unalert pilot managed to hit the lottery and fly into the tether line of an aerostat. Darwin ensued [ntsb.gov] (better formatted for easier reading here [aviation-safety.net]). One time. Ever. I'm not too concerned about those odds. Don't drink & fly. Alaska has enough bush pilots go missing already, who's going to notice one more?